Response Surface Modeling of Cu(II) Removal from Electroplating Waste by Adsorption: Application of Box–Behnken Experimental Design

The use of kaolinite‐based clay minerals as a low‐cost natural adsorbent for the removal of Cu(II) from electroplating waste leachate was studied. Batch experiments were conducted to determine the effects of varying adsorbent loading, initial pH, adsorbent dosage, and contact time. Box–Behnken design with three variables like initial pH, adsorbent dosage, and contact time at three different levels was studied to identify a significant correlation between the effects of these variables to the amount of Cu(II) adsorbed. The methodology identifies the principal experimental variables, which have the greatest effect on the adsorption process. After optimizing the input variables by using Simplex algorithm, the adsorption of Cu(II) was maximal (99.9% with a maximum (positive) standard deviation of 9.4) at pH 6.24, adsorbent dosage of 0.83 g L^?1, and contact time of 97 min, respectively. Furthermore, the experimental values are in good agreement with predicted values, the correlation coefficient and adjusted correlation coefficients were found to be 0.96 and 0.87, respectively.     

Dissolved Nutrient Distributions in Groundwater in the Mediterranean Coastal Plains – the Case of Silifke,Turkey

Total carbon, nitrogen, and phosphate parameters were studied for the first time in the groundwater in the Silifke coastal plain, which is a RAMSAR site in Turkey. Seasonal variations of these parameters in the plain were examined based on groundwater data collected from 21 wells during the winter, spring, summer, and fall seasons. Total dissolved organic carbon (DOC), inorganic carbon (DIC), inorganic phosphate (DIP), inorganic nitrogen (DIN), and total alkalinity (TAlk) average values in the groundwater were low in all seasons (<2.2 mg/L for DOC; <54 mg/L for DIC; <0.06 mg/L for DIP; <1.5 mg/L for DIN; <232 mg/L for TAlk). The results showed a strong relationship between DIC and as expected. The results indicate that the content of these parameters in the groundwater of Silifke coastal plain pose no or little risk at present. However, computed Langelier Saturation Index (LSI) values indicated that the groundwater has a tendency to form scale and CaCO₃ precipitation may occur.     

Dissipative devices for earthquake resistant composite steel structures: bolted versus welded solution

This paper investigates and compares the seismic performance of two types of innovative repairable fuse devices for earthquake resistant composite steel frames through experimental tests and numerical analyses. The fuses are energy dissipating devices consisting of steel plates that can be welded or bolted to the beam web and bottom flange. The numerical analyses performed in this study are based on the results of experimental tests carried out on beam-to-column sub-assemblages equipped with both the types of fuse devices. The main differences in terms of hysteretic behavior and failure modes of the fuses are identified through the experimental campaign. Detailed three-dimensional finite element models of the beam-to-column sub-assemblages are then created to provide a deeper insight into both the response and the effectiveness of the two investigated devices. On the basis of the results of both the experimental tests and numerical analyses, simplified models of different types of fuses are developed in order to study the effects of bolted and welded devices on the seismic response of composite steel frames. The results are then extended to the case of three-dimensional building structures with different number of storeys. The experimental and numerical investigations prove the effectiveness of the fuses and highlight the main differences between the two possible solutions.     

1-D DC Resistivity Modeling and Interpretation in Anisotropic Media Using Particle Swarm Optimization

We examine the one-dimensional direct current method in anisotropic earth formation. We derive an analytic expression of a simple, two-layered anisotropic earth model. Further, we also consider a horizontally layered anisotropic earth response with respect to the digital filter method, which yields a quasi-analytic solution over anisotropic media. These analytic and quasi-analytic solutions are useful tests for numerical codes. A two-dimensional finite difference earth model in anisotropic media is presented in order to generate a synthetic data set for a simple one-dimensional earth. Further, we propose a particle swarm optimization method for estimating the model parameters of a layered anisotropic earth model such as horizontal and vertical resistivities, and thickness. The particle swarm optimization is a naturally inspired meta-heuristic algorithm. The proposed method finds model parameters quite successfully based on synthetic and field data. However, adding 5 % Gaussian noise to the synthetic data increases the ambiguity of the value of the model parameters. For this reason, the results should be controlled by a number of statistical tests. In this study, we use probability density function within 95 % confidence interval, parameter variation of each iteration and frequency distribution of the model parameters to reduce the ambiguity. The result is promising and the proposed method can be used for evaluating one-dimensional direct current data in anisotropic media.     

Blowout mechanism of Alasehir (Turkey) geothermal field and its effects on groundwater chemistry

Anatolia region is one of the most seismically active regions in the world and has a considerably high level of geothermal energy potential. Some of these geothermal resources have been used for power generation and direct heating. Most of the high enthalpy geothermal systems are located in western part of Turkey. Alasehir is the most important geothermal site in western part of Turkey. Many geothermal wells have been drilled in Alasehir Plain to produce the geothermal fluid from the deep reservoir in the last 10 years. A blowout accident happened during a geothermal well drilling operation in Alasehir Plain, and significant amount of geothermal fluid surfaced out along the fault zone in three locations. When drilling string entered the reservoir rock about 1000 m, blowout occurred. As the well head preventer system was closed because of the blowout, high-pressure fluid surfaced out along the fault zone cutting the Neogene formation. In order to understand the geothermal fluid effects on groundwater chemistry, physical and chemical compositions of local cold groundwater were monitored from May 2012 to September 2014 in the study area. The geothermal fluid was found to be of Na–HCO₃ water type, and especially, arsenic and boron concentrations reached levels as high as 3 and 127 mg/L, respectively. The concentrations of arsenic and boron in the geothermal fluid and groundwater exceeded the maximum allowable limits given in the national and international standards for drinking water quality. According to temporally monitored results, geothermal fluid has extremely high mineral content which influenced the quality of groundwater resources of the area where water resource is commonly used for agricultural irrigation.     

Modeling of seawater intrusion in a coastal aquifer of Karaburun Peninsula,western Turkey

Seawater intrusion is a major problem to freshwater resources especially in coastal areas where fresh groundwater is surrounded and could be easily influenced by seawater. This study presents the development of a conceptual and numerical model for the coastal aquifer of Karareis region (Karaburun Peninsula) in the western part of Turkey. The study also presents the interpretation and the analysis of the time series data of groundwater levels recorded by data loggers. The SEAWAT model is used in this study to solve the density-dependent flow field and seawater intrusion in the coastal aquifer that is under excessive pumping particularly during summer months. The model was calibrated using the average values of a 1-year dataset and further verified by the average values of another year. Five potential scenarios were analyzed to understand the effects of pumping and climate change on groundwater levels and the extent of seawater intrusion in the next 10 years. The result of the analysis demonstrated high levels of electrical conductivity and chloride along the coastal part of the study area. As a result of the numerical model, seawater intrusion is simulated to move about 420 m toward the land in the next 10 years under “increased pumping” scenario, while a slight change in water level and TDS concentrations was observed in “climate change” scenario. Results also revealed that a reduction in the pumping rate from Karareis wells will be necessary to protect fresh groundwater from contamination by seawater.     

Flood forecasting and analysis within the Ulus Basin, Turkey, using geographic information systems

Floods have been the most severe natural disasters in the West Black Sea Region of Turkey for many years; therefore Ulus Basin is selected as a study area for a thorough hydrologic flood analysis. The lack of embankments around the Ulus River and careless changes to the riverbed made by villagers, resulted in major flood events in the basin, causing significant damage in the area. In this study, the hydrodynamic characteristics of the basin and the riverbed are determined by calibrating the hydraulic module of the MIKE 11 modeling system with the observed 1991 flood. Then, for the 25-, 50- and 100-year floods the highest water levels in the river are forecasted by integration of the MIKE 11 hydrologic and hydraulic modules. Afterwards, inundation maps are obtained by using together the hydraulic and GIS modules of the MIKE 11 system.     

An experimental approach for selection/elimination in stream network generalization using support vector machines

Multi-representation databases (MRDB) are used in several Geographical Information System applications for different purposes. MRDB are mainly obtained through model and cartographic generalizations. The model generalization is essentially achieved with the selection/elimination process in which a decision must be made to include or exclude the object at the target level. In this study, support vector machines (SVM) was, for the first time, used for the selection/elimination process in stream network generalization. Within this context, the attributes to be used as input data in the SVM method were determined and weighted according to the associations determined in a chi-squared independence test. 1:100,000-scale (medium resolution) stream networks were derived from two 1:24,000-scale (high resolution) stream networks with different patterns in the United States Geological Survey National Hydrography Data-sets. The derived stream networks were quite similar to the 1:100,000-scale original stream networks in both qualitative and visual aspects.     

Temporal changes of soft-bottom zoobenthic communities in and around Alsancak Harbor (Izmir Bay, Aegean Sea), with special attention to the autecology of exotic species

Temporal and spatial variation in soft‐bottom benthic communities following recovery from a pollution episode were studied between January and September 2004 in and around Alsancak Harbor, located in the polluted part of Izmir Bay (Aegean Sea, eastern Mediterranean). Samples were collected at seven stations by van Veen grab. Three additional stations were sampled by means of a beam trawl to take into account large mobile animals and for a better estimate of the local biodiversity. A total of 231 species belonging to 10 zoobenthic groups were found. Polychaetes contributed 90% of the total faunal populations and mollusks 87% of the total biomass in the area. Community parameters varied significantly among stations and sampling periods; number of species ranged from 2 to 79 per 0.1 m² grab sample; density from 20 to 81,720 ind·m^?2; biomass from 0.1 to 4190 g·m^?2; Shannon–Wiener diversity index (log₂ base) from 0.4 to 4.4; and Pielou's evenness index from 0.11 to 1.0. Collections indicate that a number of species, including those sensitive to pollution, have colonized the area where azoic conditions had been previously reported. A total of six exotic species, Streblospio gynobranchiata, Polydora cornuta, Hydroides dianthus, Hydroides elegans, Anadara demiri and Fulvia fragilis, probably transferred to the area via ballast water or hull fouling, dominated soft or hard substrata in and near Alsancak Harbor. The first two species accounted for more than 70% of the total population in the area, while A. demiri contributed the most to the biomass (93%, at station 7).